Japan's era of shoguns and samurai is long over, but the country does have one, or maybe two, surviving ninjas. Experts in the dark arts of espionage and silent assassination, ninjas passed skills from father to son - but today's say they will be the last.Japan's ninjas were all about mystery. Hired by noble samurai warriors to spy, sabotage and kill, their dark outfits usually covered everything but their eyes, leaving them virtually invisible in shadow - until they struck.Using weapons such as shuriken, a sharpened star-shaped projectile, and the fukiya blowpipe, they were silent but deadly.